Aperture

                                                                          Aperture

                                                                        ( F 2.8 below )

                                                                       (  F 16 below )

  1) The soda bottles.

2)the smaller the Aperture the more in focus it is on the main object of the photo. , the higher the Aperture it focus's less on the main object of the photo.

3)    It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field.           

4) There are 25 F stops on the canon camera.